Omar Mateen’s employer G4S did not fire him or take away his company pistol after the FBI investigated the Muslim security professional for statements professing loyalty to jihadist organizations.

NBC News has learned that the security firm that employed Orlando shooter Omar Mateen concluded that allegations about his inflammatory comments while an armed guard in 2013 were serious enough to transfer him to an unarmed position and to conduct a special background check to see if he had become a problem employee.

But the company, G4S Secure Solutions USA Inc., dropped the matter of whether Mateen should continue to serve as a guard shortly after a check of local, state and national criminal databases showed he had a clean record, a G4S spokesman told NBC News. The company also did not take away his company-issued service weapon, a .38 handgun.

That decision, coupled with the fact that Mateen underwent three separate inquiries by the FBI in 2013 and 2014, raises questions about whether G4S — the U.S. subsidiary of one of the world’s largest security firms – properly vetted Mateen in the years before Sunday’s mass shooting at the Pulse nightclub that killed 49 people and injured more than 50 others.

The company official acknowledged in an interview with NBC News that it is now conducting a thorough internal inquiry to determine if it missed any warning signs that should have prompted it to take away Mateen’s company-issued service weapon and to either discipline or fire him.